Chain-type jack for handling tensile and compressive loads

ABSTRACT

An improved jack includes a fixed housing through which an elongated drive chain extends. A sprocket within the housing advances and retracts the chain through the housing via forward and rearward exit ports to provide a desired change in the direction of motion of the chain. The portion of the chain extending from the rearward port of the housing is further rotated back on itself through engagement with a floating guide member. The rear end of the chain is suitably anchored. The combination of the guiding member and the anchoring means serves to restrict the overall rearward extension of the guide member to a prescribed fraction of the forward extension and permits the form factor of the jack in its retracted position to be smaller than that in its extended position. The adjacent links of the chain include interlocking, axially aligned projections for withstanding compressive as well as tensile loads.

United States Patent [191 11] 3,831,455 Patrignani Aug. 27,.1974

[ CHAIN-TYPE JACK FOR HANDLING Primary ExaminerSamuel Scott TENSILE AND COMPRESSIVE LOADS Inventor: Theo Patrignani, Paris, France Assignee: Manufacture de Machines du Haut Rhin, Mulhouse-Bourtzwiller, France Filed: Apr. 24, 1972 Appl. No.1 246,621

Foreign Application Priority Data Apr. 26, 1971 France 7l.l4792 References Cited UNITED STATES PATENTS 7/1933 Long 254/DlG. 6 6/1972 Nagin 74/8921 X Assistant Examiner-F. D. Shoemaker ABSTRACT An improved jack includes a fixed housing through which an elongated drive chain extends. A sprocket within the housing advances and retracts the chain through the housing via forward and rearward exit ports to provide a desired change in the direction of motion of the chain. The portion of the chain extending from the rearward port of the housing is further rotated back on itself through engagement with a floating guide member. The rear end of the chain is suitably anchored. The combination of the guiding member and the anchoring means serves to restrict the overall rearward extension of the guide member to a prescribed fraction of the forward extension and permits the form factor of the jack in its retracted position to be smaller than that in its extended position. The adjacent links of the chain include interlocking, axially aligned projections for withstanding compressive as well as tensile loads.

8 Claims, 5 Drawing Figures v 3331.455 m w 4 PAIENIEflmsznsu l a. Q

FIG, 3B

FIG. IA

CHAIN-TYPE JACK FOR HANDLING TENSILE AND COMPRESSIVE LOADS BACKGROUND OF THE INVENTION Many jacks of the chain-driven type are bulky and inconvenient to use, particularly in tight spaces. In the main, this is due to the fact that such jack, when its chain is in a fully retracted position when out of use, has a form factor that takes up the same linear space as when the jack is in its fully extended, operative position. Moreover, many such chain-drive jacks are inherently unable to withstand compressive loads, and their maximum extension in the forward direction is generally fixed in the factory and cannot be conveniently modified to provide additional flexibility.

SUMMARY OF THE INVENTION These disadvantages are overcome with a compact retractable chain drive jack constructed in accordance with the invention. lllustratively, the jack employs as a drive chain a plurality of flexibly joined links wherein adjacent links have interlocking, axially aligned projections which cooperate to resist compressive loads.

A first drive sprocket is rotatably mounted within a fixed housing through which the drive chain extends for selectively advancing and retracting a front end of the chain. The housing has a front port extending in a first direction and a rear port extending in a second direction. The rear end of the chain is anchored. A guide member such as an auxiliary sprocket is freely mounted in engagement with the portion of the chain extending between the rear port of the housing and the anchor, and the sprocket is arranged to freely translate in the second direction.

With this arrangement, the extension or retraction of the front end of the chain by a predetermined distance in a first direction will cause the freely floating guide member to simultaneously translate in the second direction by one-half of the distance traversed by the front end. Consequently, the total space that need be provided for the jack in the second direction in its fully retracted position may be restricted to a dimension not more than one-half the maximum forward extension of the chain.

In another embodiment, an additional guide member may be disposed on the housing in engagement with a portion of the chain intermediate the floating guide member and the anchoring means in order to provide a further reversal of motion of the drive chain. When such second guide member (illustratively a sprocket)is driven in synchronism with the main drive sprocket at one-third the angular speed of the main drive sprocket and the rear end of the chain is anchored to the floating guide member, the floating guide member will be restricted to a translational movement in a second direction equal to one-third the total forward extension of the chain.

BRIEF DESCRIPTION OF THE DRAWING The invention will be further set forth in the following detailed description taken in conjunction with the appended drawing in which:

FIGS. la and lb are elevational views of a first'type of chain-type jack constructed in accordance with the invention when in its fully extended and fully retracted positions respectively, the direction of retraction being DETAILED DESCRIPTION Referring now to the drawing, the reference numeral 11 in FIG. 1 indicates generallyan interlinked drive chain of the constructed type, e.g., described in U.S. Pat. No. 3,358,524 issued Dec. 19, 1967. The chain illustratively includes a plurality of successive links 1-] which are joined by pins 2222. Each link includes a main body portion 23 and a projection 24 integral with the body portion. As taught by the above-mentioned patent, the projections 24 associated with adjacent links 1 may be mounted on opposite transverse portions of the main link body 23. Successive projections 24 may be offset in opposite transverse directions and therefore are aligned in the same plane in interlocking relation as shown. Such coplanar construction permits each point of the chain to have the same overall thickness, and the interlocking projections effectively resist compressive as well as tensile loads.

The chain 11 extends through a fixed housing 4 and terminates at its forward end in a loadengaging member 7. In particular, a rear portion 9 of the chain is fixedly connected to the housing via a pin 26 and is aligned in a vertical direction as viewed in the drawing. The pin 26 is disconnectable from the chain and the housing to permit additional links to be added to the chain to increase its maximum range or conversely, to remove links from the chain as desired.

The chain 11 extends into the housing 4 via a vertically disposed rear exit port 27, proceeds around a drive sprocket 3 rotatably mounted within the housing, and emerges through a horizontally disposed forward port 28. A conventional motor or other suitable drive means (not shown) is provided in the housing for rotating the drive sprocket 3.-in one of two opposite directions such that, for example, a counter-clockwise rotation of the sprocket 3 will advance the front end 7 of the chain to the right through the front port 28, and a clockwise rotation of the sprocket 3 will retract the chain through the housing and out of the rear port 27.

An auxiliary sprocket 8 having a diameter similar and anaxis of rotation parallel to that of the sprocket 3, is located above the sprocket 3. The sprocket 8 engages the portion of the .chain extending rearwardly from the port 27 and terminating at the anchoringpin 26. Consequently, the sprocket 8 acts as a guiding member which reverses the direction of motion of the engaged portion of the chain.

The sprocket 8 is permitted to float with respect to the housing and is therefore free to undergo translational movement in the vertical direction parallel to'the exit port 27 when the forward end 7 of the chain is in -its fully extended position, the sprocket 8 is in its lowermost position as shown. As the chain is driven into its fully retracted position, the sprocket 8 moves upward I as shown and, because the rear end 9 of the chain is anchored to the housing 4, the total linear travel of the sprocket 8 is limited to one-half the maximum extension of the forward end 7 of the chain. Consequently, the total distance that need be provided in the vertical direction to accommodate the jack need only be onehalf that of its total horizontal extension.

An alternative form of the jack of FIG. 1 is shown in FIG. 2. The arrangements of FIGS. 1 and 2 are generally similar except that the rearward port 27 of the housing emerges parallel to the forward port 28, whereby the chain is subjected to a full 180 reversal as it extends through the housing around the drive sprocket 3. This arrangement is advantageous where the jack must operate in confined vertical quarters, and it will be observed that, because of the floating sprocket 8 and the fixed anchor at the rear end of the chain, the jack in its retracted position will only require one-half the total horizontal space as that taken up by the maximum extension of the forward chain 7.

if an even further decrease of the form factor of the jack in its fully retracted position is required, the arrangement indicated in FIGS. 3A and 3B may be employed. As in FIG. 1, the chain 11 is rotated through 90 in the housing as it extends around the drive sprocket 3 between the forward port 28 and the rearward port 27. Additionally, in a manner similar to FIG. 1, after the chain emerges rearwardly through the port 27, the direction of motion of the chain is reversed on itself by being passed around a floating guide member which is arranged to translate freely in a direction parallel to the vertical axis of the port 27. However, in the arrangement of FIGS. 3A and 35, an additional reversal of motion of the chain is provided between the anchoring pin 26 and the floating guide member which in FIGS. 3A and 3B is shown in the form of a polygonal member 31. The member 31 has a plurality of arcuately spaced peripheral rollers 32 which engage the adjacent portion of the chain 1. Also, the pin 26 is located on the floating guide member 31 rather than on the fixed housing 4. Such additional motion reversal is provided by a second guide member in the form of a drive sprocket 13 which is mounted for rotation on the housing 4 and whose axis is parallel to the drive sprocket 3. A suitable stepdown transmission schematically indicated at 14 interconnects the drive sprockets 3 and 13 such that the rotation of the drive sprocket 3 synchronously rotates the drive sprocket 13 at one-third the angular speed of the sprocket 3. Because of this arrange ment and the location of the anchor pin 26 on the guide member 31, the rotation of the sprocket 13 at one-third the speed on the sprocket 3 will cause the total translation of the guiding member 31 in the vertical direction to be only one-third that of the total horizontal extension of travel of the front end 7 of the chain in the forward direction. Consequently, the maximum vertical dimension of the jack can be restricted to one-third of its maximum extended length.

In the foregoing, the invention has been described in connection with preferred arrangements thereof. Many variations and modifications will now occur to those skilled in the art. It is accordingly desired that the scope of the appended claims not be limited to the specific disclosure herein contained.

What is claimed is:

1. A mechanical jack, comprising:

a motion transmitting drive chain having a forward end and a rearward end, and a plurality of successive, flexibly connected links, adjacent links having interlocking, axially aligned projections for resisting compressive loads;

a stationary housing having a forward exit port extending in a first direction, a rearward exit port extending in a second direction and an interior space through which the forward and rearward ports communicate, the drive chain extending through the housing via the forward and rearward ports;

a first drive sprocket rotatably mounted in the housing in engagement with a portion of the chain located intermediate the forward and rearward ports;

means for rotating the first sprocket in a selectable one of two opposite directions for respectively advancing and retracting the front end of the chain in the first direction;

anchoring means for fixedly aligning the rearward end of the chain parallel to the second direction; and

first guide means engaging a portion of the chain between the rearward port and the anchoring means for reversing the direction of said engaged portion of the chain, the first guide means being mounted for free translational movement in the second direction.

2. A jack as defined in claim 1, in which the first guide means comprises an auxiliary sprocket having an axis parallel to the first drive sprocket, and the anchoring means comprising means for affixing the rearward end of the chain to the housing.

3. A jack as defined in claim 2, in which the rearward port extends perpendicular to the forward port so that the chain is rotated as it passes through the housing.

4. Ajack as defined in claim 1 in which the anchoring means comprises means for affixing the rearward end of the chain to the first guide means, and the jack further comprises second guide means mounted on the housing in engagement with a portion of the chain between the first guide means and the anchoring means for reversing the direction of motion of the associated portion of the chain.

5. A jack as defined in claim 4 in which the second guide means comprises a second drive sprocket rotatably mounted on the housing and having an axis parallel to the first drive sprocket, and in which the rotating means comprises means for driving the second drive sprocket synchronously with and at an angular speed bearing a fixed ration to the speed of the first drive sprocket.

6. A jack as defined in claim 5 in which the driving means rotates the second drive sprocket located at a speed equal to one-third the speed of the first drive sprocket.

7. A jack as defined in claim 4 in which the first guide means includes a plurality of arcuately spaced peripheral rollers around which the chain is extended.

8. A mechanical jack, comprising:

a motion transmitting drive chain having a forward end and a rearward end, and a plurality of successive, flexibly connected links, adjacent links having interlocking, axially aligned projections for resisting compressive loads;

end of the chain parallel to a second direction; and

first guide means engaging a portion of the chain be-- tween the second port and the anchoring means for reversing the direction of said engaged portion of the chain, the first guide means being mounted for free translational movement in the second direction, and said second port extends parallel to the first port and in the same sense so that the chain is .rotated as it passes through the housing. 

1. A mechanical jack, comprising: a motion transmitting drive chain having a forward end and a rearward end, and a plurality of successive, flexibly connected links, adjacent links having interlocking, axially aligned projections for resisting compressive loads; a stationary housing having a forward exit port extending in a first direction, a rearward exit port extending in a second direction and an interior space through which the forward and rearward ports communicate, the drive chain extending through the housing via tHe forward and rearward ports; a first drive sprocket rotatably mounted in the housing in engagement with a portion of the chain located intermediate the forward and rearward ports; means for rotating the first sprocket in a selectable one of two opposite directions for respectively advancing and retracting the front end of the chain in the first direction; anchoring means for fixedly aligning the rearward end of the chain parallel to the second direction; and first guide means engaging a portion of the chain between the rearward port and the anchoring means for reversing the direction of said engaged portion of the chain, the first guide means being mounted for free translational movement in the second direction.
 2. A jack as defined in claim 1, in which the first guide means comprises an auxiliary sprocket having an axis parallel to the first drive sprocket, and the anchoring means comprising means for affixing the rearward end of the chain to the housing.
 3. A jack as defined in claim 2, in which the rearward port extends perpendicular to the forward port so that the chain is rotated 90* as it passes through the housing.
 4. A jack as defined in claim 1 in which the anchoring means comprises means for affixing the rearward end of the chain to the first guide means, and the jack further comprises second guide means mounted on the housing in engagement with a portion of the chain between the first guide means and the anchoring means for reversing the direction of motion of the associated portion of the chain.
 5. A jack as defined in claim 4 in which the second guide means comprises a second drive sprocket rotatably mounted on the housing and having an axis parallel to the first drive sprocket, and in which the rotating means comprises means for driving the second drive sprocket synchronously with and at an angular speed bearing a fixed ration to the speed of the first drive sprocket.
 6. A jack as defined in claim 5 in which the driving means rotates the second drive sprocket located at a speed equal to one-third the speed of the first drive sprocket.
 7. A jack as defined in claim 4 in which the first guide means includes a plurality of arcuately spaced peripheral rollers around which the chain is extended.
 8. A mechanical jack, comprising: a motion transmitting drive chain having a forward end and a rearward end, and a plurality of successive, flexibly connected links, adjacent links having interlocking, axially aligned projections for resisting compressive loads; a stationary housing having first and second ports, an interior space through which said ports communicate, the drive chain extending through the housing via the first and second ports; a first drive sprocket rotatably mounted in the housing in engagement with a portion of the chain located intermediate the first and second ports; means for rotating the first sprocket in a selectable one of two opposite directions for respectively advancing and retracting the front end of the chain in a first direction; anchoring means for fixedly aligning the rearward end of the chain parallel to a second direction; and first guide means engaging a portion of the chain between the second port and the anchoring means for reversing the direction of said engaged portion of the chain, the first guide means being mounted for free translational movement in the second direction, and said second port extends parallel to the first port and in the same sense so that the chain is rotated 180* as it passes through the housing. 